     (set-alpha 0.8)
     view))
 
-(def m-per-h->km-per-h (partial * 3.6))
+(def meters-per-hour->kilometers-per-hour (partial * 3.6))
+(defn- seconds->minutes [s] (/ s 60))
+(defn- string-date->millis [str-date]
+  (.getTime
+    (clojure.instant/read-instant-date str-date)))
 
 (defn -main
   [& args]

         :per_page     200}})
      :body)))

(defn- to-millis [str-date]
  (.getTime
    (clojure.instant/read-instant-date str-date)))

(defn- ts-plot [x y & options]
  (doto
    (apply time-series-plot*

        :group-by ($ :type)
        :title "Activity duration over time"
        :x-label "time"
        :y-label "activity's elapsed time (minutes)"))
    ))